Abstract:

A superconductivity utilizing support mechanism comprises a
superconductive coil and a ferromagnetic body. One of the ferromagnetic
body, so constituted as to slide in a direction of a center axis of the
superconductive coil, and the superconductive coil, so constituted as to
slide in a direction of the center axis thereof, is floated and supported
relative to the other by axial magnetic attraction caused by a center
plane of the superconductive coil and a center plane of the ferromagnetic
body moving apart from each other.

Claims:

1. A superconductivity utilizing support mechanism comprising:a
superconductive coil; anda ferromagnetic body,one of the ferromagnetic
body, so constituted as to slide in a direction of a center axis of the
superconductive coil, and the superconductive coil, so constituted as to
slide in a direction of the center axis thereof, being floated and
supported relative to the other by axial magnetic attraction caused by a
center plane of the superconductive coil and a center plane of the
ferromagnetic body moving apart from each other.

2. The superconductivity utilizing support mechanism according to claim 1
further comprising:a rotor that includes the ferromagnetic body,the rotor
being so constituted as to rotate on the center axis of the
superconductive coil and to slide in a direction of the center axis of
the superconductive coil,wherein the rotor is floated and supported
relative to the other by the axial magnetic attraction caused by the
center plane of the superconductive coil and the center plane of the
ferromagnetic body moving apart from each other.

3. The superconductivity utilizing support mechanism set forth in claim 1
further comprising:a movable body that includes the superconductive coil;
anda track that includes the ferromagnetic body, the movable body being
so constituted as to move along the track and to slide in a direction of
the center axis of the superconductive coil,wherein the movable body is
floated and supported relative to the other by the axial magnetic
attraction caused by the center plane of the superconductive coil and the
center plane of the ferromagnetic body moving apart from each other.

4. A permanent magnet utilizing support mechanism comprising:an axially
magnetized ring permanent magnet, anda ferromagnetic body,one of the
ferromagnetic body, so constituted as to slide in a direction of a center
axis of the ring permanent magnet, and the ring permanent magnet, so
constituted as to slide in a direction of the center axis thereof, being
floated and supported relative to the other by axial magnetic attraction
caused by a center plane of the ring permanent magnet and a center plane
of the ferromagnetic body moving apart from each other.

5. The permanent magnet utilizing support mechanism set forth in claim 4,
whereina rotor that includes the ferromagnetic body,the rotor being so
constituted as to rotate on the center axis of the ring permanent magnet
and to slide in a direction of the center axis of the ring permanent
magnet,wherein the rotor is floated and supported relative to the other
by the axial magnetic attraction caused by the center plane of the ring
permanent magnet and the center plane of the ferromagnetic body moving
apart from each other.

Description:

TECHNICAL FIELD

[0001]This invention relates to a mechanism for floating and supporting a
rotor and a movable body by utilizing superconductivity and a permanent
magnet.

BACKGROUND ART

[0002]A control type magnetic bearing is known as the most general type of
a non-contact thrust bearing. For example, there is a control type
magnetic bearing so constituted as to support a rotor by a bearing that
utilizes an electromagnet as shown in FIG. 5(a), or a control type
magnetic bearing having a constitution as disclosed in Non-Patent
Literature 1. There is also a bearing that utilizes superconductivity.
The bearing developed utilizes superconducting bulk and a permanent
magnet. For example, there is a bearing provided with a permanent magnet
under a rotor, and the permanent magnet is disposed to face
superconducting bulk, as shown in FIG. 5(b) (see also Patent Literature
1). There are also bearings having a constitution as disclosed in
Non-Patent Literatures 2 and 3. [0003]Non-Patent Literature 1: "KOYO
Engineering Journal No. 158 (2000)", KOYO SEIKO CO., LTD., printed on
Jul. 23, 2000), pages 16 to 20 [0004]Patent Literature 1: Unexamined
Japanese Patent Publication No. 2001-343020 [0005]Non-Patent Literature
2: "KOYO Engineering Journal No. 156 (1999)", KOYO SEIKO CO., LTD., pages
9 to 14 [0006]Non-Patent Literature 3: "KOYO Engineering Journal No. 151
(1997)", KOYO SEIKO CO., LTD., pages 12 to 16

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

[0007]There are problems as below in these types of thrust bearings. For
example, although a control type magnetic bearing is widely put into
practical use, large electric power is required to the thrust bearings
having very large axial force. Rotation loss occurs due to fluctuation of
the magnetic field along the rotational direction. Additionally, there is
limitation of manageable weight in a thrust bearing that utilizes
superconducting bulk. There is a problem that a thrust bearing that
utilizes superconducting bulk is not practicable to float and support a
large-sized body.

[0008]The first object of the present invention is to propose a mechanism
for floating and supporting a rotor and a movable body by utilizing
superconductivity, which is effective in floating and supporting
large-sized rotor and movable body.

[0009]The support mechanism that utilizes superconductivity is effective
in floating and supporting a large-sized rotor or movable body as noted
above. However, a permanent magnet may be utilized if there is no
intention to support a large-sized rotor, etc. A non-contact thrust
bearing that utilizes a permanent magnet may have a constitution that
utilizes attraction of the permanent magnet to a ferromagnetic body. Two
methods are considered as the example. That is, there is a method of
generating thrust force to an extent that the ferromagnetic body is not
completely attracted so as to mechanically support the rest of the load,
or a method of using an additional control type magnetic bearing so as to
support the load in a completely non-contact manner.

[0010]However, it is difficult to achieve a completely non-contact
constitution in the former constitution. As a result, a substantial
amount of the load has to be supported by mechanical contact. A
completely non-contact constitution can be achieved by the latter
constitution. However, use of an additional control type magnetic bearing
is indispensable. Accordingly, the latter constitution is not desirable
in view of costs and energy loss caused.

[0011]The second object of the present invention is to propose a mechanism
for floating and supporting a rotor and a movable body by utilizing a
permanent magnet, which is effective in floating and supporting
relatively light rotor and movable body.

Means to Solve the Problems

[0012]A superconductivity utilizing support mechanism set forth in claim 1
which was made to achieve the first object above includes: a
superconductive coil (1, 21, 31: For the sake of easy understanding
toward the present invention, reference numbers used under the section
name "BEST MODE FOR CARRYING OUT THE INVENTION" are given as required in
this section. However, it should not be considered that the claims shall
be limited by these reference numbers)) and a ferromagnetic body (2a,
22a, 32a). One of the ferromagnetic body (2a, 22a, 32a), so constituted
as to slide in a direction of a center axis (1a, 21a, 31a) of the
superconductive coil (1, 21, 31), and the superconductive coil (1, 21,
31), so constituted as to slide in a direction of the center axis (1a,
21a, 31a), is floated and supported relative to the other by axial
magnetic attraction caused by a center plane (S1, S11) of the
superconductive coil (1, 21, 31) and a center plane (S2, S13) of the
ferromagnetic body (2a, 22a, 32a) moving apart from each other. It should
be noted that the "center plane of coil" does not necessarily correspond
to a geometric center of coil.

[0013]This superconductivity utilizing support mechanism can be applied to
various objects. For example, if applied to a thrust bearing of a rotor,
the thrust bearing will be as shown in claim 2. That is, the thrust
bearing is provided with a rotor (2, 22) including the ferromagnetic body
(2a, 22a). The rotor (2, 22) is so constituted as to rotate on the center
axis (1a, 21a) of the superconductive coil (1, 21). The rotor (2, 22) is
so constituted as to slide in a direction of the center axis (1a, 21a) of
the superconductive coil (1, 21). The rotor (2, 22) is supported and
floated by axial magnetic attraction caused by the center plane (S1) of
the superconductive coil (1, 21) and the center plane (S2) of the
ferromagnetic body (2a, 22a) moving apart from each other. Thereby,
essentially stable and strong thrust bearing force is obtained to float
and support the rotor (2, 22) in a direction of the center axis (1a, 21a)
of the superconductive coil (1, 21).

[0014]If applied to the thrust bearing of such rotor, the
superconductivity utilizing support mechanism may further adopt the
following constitution. That is, the ferromagnetic body (22a) has a
substantially ring shape or a substantially columnar shape, and is
provided at its axially upper and lower ends with flange portions (221a)
protruding radially outward. An annular member (26) is also provided
which has a substantially U-shaped cross section and retains a cryogenic
container (23) that accommodates the superconductive coil (21). The
annular member (26) has an opening which faces radially inward, and is
provided with convex portions (26a) which are located in vicinity of
axially upper and lower ends of the superconductive coil (21) and are
smaller in inner diameter than the superconductive coil (21). Moreover,
the flange portions (221a) formed at the axially upper and lower ends of
the ferromagnetic body (22a) are arranged to face the convex portions
(26a) of the annular member (26).

[0015]The convex portions (26a) of the annular member (26) function as a
magnetic path of magnetic force generated by the superconductive coil
(21).

[0016]The convex portions (26a) of the annular member (26) are arranged to
face the flange portions (221a) formed at the axially upper and lower
ends of the ferromagnetic body (22a). Accordingly, if the convex portions
(26a) of the annular member (26) and the flange portions (221a) of the
ferromagnetic body (22a) are in positions to face each other, the center
plane (S1) of the superconductive coil (21) and the center plane (S2) of
the ferromagnetic body (22a) coincide with each other. In this case,
axial magnetic attraction does not work. However, if the center plane
(S1) of the superconductive coil (21) and the center plane (S2) of the
ferromagnetic body (22a) are axially shifted relative to each other from
the facing position, the center plane (S1) of the superconductive coil
(21) and the center plane (S2) of the ferromagnetic body (22a) are
separated. Therefore, axial magnetic attraction works.

[0017]Also, if applied to a movable body support mechanism of linear move
type, the movable body support mechanism will be as shown in claim 3.
That is, the movable body support mechanism is provided with: a movable
body (33) including the superconductive coil (31), and a track (32)
including the ferromagnetic body (32a). The movable body (33) is so
constituted as to move along the track (32). The movable body (33) is
also constituted to slide in a direction of the center axis (31a) of the
superconductive coil (31). The movable body (33) is floated and supported
by axial magnetic attraction caused by the center plane (S11) of the
superconductive coil (31) and the center plane (S13) of the ferromagnetic
body (32a) moving apart from each other. Thereby, essentially stable and
strong thrust bearing force is obtained to float and support the movable
body (33) in a direction of the center axis (31a) of the superconductive
coil (31).

[0018]In the case of combination of a permanent magnet and superconducting
bulk proposed in the aforementioned prior art, it is difficult to raise
precision in shape, etc. of both the permanent magnet and the
superconducting bulk. There is a problem in stable support. On the other
hand, a superconductive coil is utilized in the superconductivity
utilizing support mechanism of the present invention. In the case of this
superconductive coil, precision in shape can be easily raised. It is
advantageous in stable float and support. Also, the rotor or the movable
body to be supported may only include a ferromagnetic body made of steel
or the like, for example. It is also advantageous in that no special kind
of material is require d.

[0019]Here, the reason will be given why there has been no concept like
the present invention before. In the technical trend regarding a bearing
that utilizes superconductivity, there is a predominant premise of
combination of a permanent magnet and superconducting bulk. On the
premise of the combination, research and development are stimulated with
such intention as to remove the above restrictions by performance upgrade
of material. Ideally, this combination is a proper constitution which
provides support in both floating direction and horizontal direction.
However, in reality, it is difficult to raise precision in shape, etc. of
both the permanent magnet and the superconducting bulk. There is a
problem in stable support. The inventor of the present application has
focused such problem and noted that, in the case of a superconductive
coil, a strong magnetic field can be easily generated and precision in
shape can be easily raised. If a ferromagnetic body is arranged within
such a range that the magnetic attraction may become stronger as the
ferromagnetic body goes farther in a direction of a center axis of the
superconductive coil from a center plane of the superconductive coil, the
center plane of the coil is assumed as a stabilization point and a stable
spring characteristic is obtained. The inventor has found that the above
fact is usable and invented the aforementioned invention. Thereby, a
support mechanism for heavy load can be implemented which has never been
imagined before.

[0020]Specifically, if a support object is a rotor as in the
superconductivity utilizing support mechanism set forth in claim 2,
circular magnetic field distribution having extremely less distortion can
be easily obtained by utilization of a superconductive coil. Accordingly,
even from such viewpoint, there is a large advantage over the combination
of a permanent magnet and bulk. Use of a circular superconductive coil
also provides such an advantage that no eddy current loss or hysteresis
loss may occur, in principle, even if a rotor having a ferromagnetic body
is rotated while non-contact thrust force is maintained.

[0021]A permanent magnet utilizing support mechanism set forth in claim 4
which was made to achieve the second object above includes an axially
magnetized ring permanent magnet (51), and a ferromagnetic body (52a).
One of the ferromagnetic body (52a), so constituted as to slide in a
direction of a center axis of the ring permanent magnet (51), and the
ring permanent magnet (51), so constituted as to slide in a direction of
the center axis of the ring permanent magnet (51), is floated and
supported relative to the other by axial magnetic attraction caused by a
center plane of the ring permanent magnet (51) and a center plane of the
ferromagnetic body (52a) moving apart from each other.

[0022]This permanent magnet utilizing support mechanism can be applied to
various objects. For example, if applied to a thrust bearing of a rotor,
the thrust bearing will be as shown in claim 5. That is, the thrust
bearing is provided with a rotor (52) including the ferromagnetic body
(52a). The rotor (52) is so constituted as to rotate on the center axis
of the ring permanent magnet (51). Also, the rotor (52) is so constituted
as to slide in a direction of the center axis of the ring permanent
magnet (51). The rotor (52) is floated and supported by axial magnetic
attraction caused by a center plane of the ring permanent magnet (51) and
a center plane of the ferromagnetic body (52a) moving apart from each
other. Thereby, essentially stable and strong thrust bearing force is
obtained to float and support the rotor (52) in a direction of the center
axis of the ring permanent magnet (51).

[0023]If applied to the thrust bearing of such rotor, the following
constitution may be adopted. That is, the ferromagnetic body (52a) has a
substantially ring shape or a substantially columnar shape, and is
provided at its axially upper and lower ends with flange portions
protruding radially outward. A ferromagnetic body ring (56) having a
smaller diameter than the ring permanent magnet (51) is fixed to the
axially upper and lower ends of the ring permanent magnet (51) in a
concentric fashion. Moreover, the flange portions formed at the axially
upper and lower ends of the ferromagnetic body (52a) are arranged to face
the ferromagnetic body ring (56) fixed to the axially upper and lower
ends of the ring permanent magnet (51).

[0024]The ferromagnetic body ring (56) fixed to the axially upper and
lower ends of the ring permanent magnet (51) functions as a magnetic path
of magnetic force generated by the permanent magnet (51). The
ferromagnetic body ring (56) is arranged to face the flange portions
provided at the axially upper and lower ends of the ferromagnetic body
(52a). Accordingly, if the ferromagnetic body ring (56) and the flange
portions of the ferromagnetic body (52a) are in positions to face each
other, the center plane of the ring permanent magnet (51) and the center
plane of the ferromagnetic body (52a) coincide with each other. In this
case, axial magnetic attraction does not work. However, if the center
plane of the ring permanent magnet (51) and the center plane of the
ferromagnetic body (52a) are axially shifted relative to each other from
the facing position, the center plane of the ring permanent magnet (51)
and the center plane of the ferromagnetic body (52a) are separated. In
this case, axial magnetic attraction works.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is a schematic end view of a superconductivity utilizing
support mechanism according to a first embodiment.

[0026]FIG. 2 is a schematic end view of the superconductivity utilizing
support mechanism in variation of the first embodiment.

[0027]FIG. 3 (a) is a schematic perspective view of a superconductivity
utilizing support mechanism according to a second embodiment, and (b) is
an end view taken from a section A-A of (a).

[0028]FIG. 4 is a schematic end view of a permanent magnet utilizing
support mechanism according to a third embodiment.

[0032]Embodiments of the present invention will be explained hereafter, by
way of the drawings.

First Embodiment

[0033]FIG. 1 is a schematic end view of a superconductivity utilizing
support mechanism according to a first embodiment.

[0034]As shown in FIG. 1, the superconductivity utilizing support
mechanism is provided with a superconductive coil 1, a rotor 2 including
a ferromagnetic body 2a made of steel or the like, a cryogenic container
3 that accommodates the superconductive coil 1, a control bearing 5, and
a casing 7 that accommodates the superconductive coil 1, the rotor 2, the
cryogenic container 3, and the control type magnetic bearing 5.

[0035]The rotor 2 is rotatably supported on a center axis (coil center
axis) 1a of the superconductive coil 1. The rotor 2 is so constituted as
to slide in a direction of the coil center axis 1a. Particularly, a
rotation shaft 2b of the rotor 2 is provided to penetrate the center of
the disk-shaped ferromagnetic body 2a. The rotor 2 is so constituted as
to provide non-contact support (for the rotation shaft 2b) at both an
upper end and a lower end of the rotation shaft 2b by the control type
magnetic bearing 5 utilizing an electromagnet or the like. Thereby, the
rotor 2 is rotatably supported on the coil center axis 1a and is able to
slide in a direction of the coil center axis 1a. Not such magnetically
controlled bearing as above but an air bearing can also achieve a
non-contact bearing. Also, if not particular about being non-contact, a
mechanical bearing utilizing a bearing or the like may be used.

[0036]The superconductive coil 1 is formed into a regular annular shape.
The superconductive coil 1 is arranged to enclose the ferromagnetic body
2a of the rotor 2. Particularly, the cryogenic container 3 is fixed on an
inner peripheral surface of the casing 7. The superconductive coil 1 is
arranged inside the cryogenic container 3. The ferromagnetic body 2a of
the rotor 2 is then arranged to be enclosed by the annular
superconductive coil 1. More specifically, the ferromagnetic body 2a of
the rotor 2 is arranged within such a predetermined range that magnetic
attraction may become stronger as a center plane (ferromagnetic body
center plane) S2 of the ferromagnetic body 2a and a center plane (coil
center plane) S1 of the superconductive coil 1 are separated away in a
direction of the coil center axis 1a, so that the rotor 2 is supported in
a direction of the rotation shaft 2b (of the rotor 2). Generally, the
coil center plane S1 does not necessarily coincide with a geometric
center of the superconductive coil 1. However, in the present embodiment,
the geometric center coincides with the coil center plane S1 since the
superconductive coil 1 is symmetrically formed. Also, the coil center
axis 1a extends in a direction of a normal line of the coil center plane
S1. The ferromagnetic body 2a of the present embodiment is formed into a
symmetric disk shape. Thus, a geometric center plane of the disk-shaped
ferromagnetic body 2a is referred as the ferromagnetic body center plane
S2.

[0037]Here, explanation is given on the meaning of "the ferromagnetic body
2a of the rotor 2 is arranged within such a predetermined range that
magnetic attraction may become stronger as the ferromagnetic body center
plane S2 and the coil center plane S1 are separated away in a direction
of the coil center axis 1a". In case that the ferromagnetic body 2a is
arranged in a magnetic field formed by the superconductive coil 1,
magnetic attraction that pulls back the ferromagnetic body 2a is
cancelled and no axial force is generated, if the ferromagnetic body
center plane S2 and the coil center plane S1 coincide with each other. On
the other hand, as shown in FIG. 1, if the ferromagnetic body center
plane S2 and the coil center plane S1 do not coincide with each other,
magnetic attraction is generated which pulls back the ferromagnetic body
2a toward such a direction that the ferromagnetic body center plane S2
and the coil center plane S1 may coincide with each other. Force (spring
force) that would return the ferromagnetic body 2a to the center plane S1
of the superconductive coil 1 is generated. It can be said that "magnetic
attraction becomes stronger as the ferromagnetic body center plane S2 and
the coil center plane S1 are separated away in a direction of the coil
center axis 1a (that is, as the ferromagnetic body center plane S2 is
drawing away from the coil center plane S1 in a direction of the coil
center axis 1a)" if a distance between the ferromagnetic body center
plane S2 and the coil center plane S1 is within the predetermined range.
However, outside the predetermined range, "magnetic attraction becomes
weaker as the ferromagnetic body center plane S2 is drawing away from the
coil center plane S1 in a direction of the coil center axis 1a".
Accordingly, in the present embodiment, the ferromagnetic body 2a is
arranged within such a predetermined range that "magnetic attraction may
become stronger as the ferromagnetic body center plane S2 and the coil
center plane S1 are separated away in a direction of the coil center axis
1a" as in the former description.

[0038]Such arrangement offers an essentially stable and strong bearing
force in floating and supporting the rotor 2 in a direction of the coil
center axis 1a. Also, such arrangement provides advantages as below in
comparison to the combination of a permanent magnet and superconductive
bulk proposed in prior art.

[0039](1) In the case of the conventional constitution, it is difficult to
raise precision of the shape, etc. of both the permanent magnet and the
superconducting bulk. There is a problem in stable support. In contrast,
the superconductivity utilizing support mechanism according to the
present embodiment utilizes the superconductive coil 1. It is easy to
raise precision in shape in the case of the superconductive coil 1. It is
advantageous in stable float and support.

[0040](2) In the case of the support mechanism utilizing superconductive
bulk, there is limitation in manageable weight. Such support mechanism is
not realistic to be used for a large-sized support object. On the other
hand, the present embodiment utilizes the superconductive coil 1. It is
comparatively easy to generate a strong magnetic field in the case of the
superconductive coil 1. Also, it is comparatively easy to obtain the
large-sized the superconductive coil 1. Accordingly, it is easy to
relatively increase manageable weight. As such, without use of the
superconductive coil 1, the coil capable of generating a necessary
magnetic field may become very large when weight of a support object is
increased, or, depending on the weight of the support object, generation
of a necessary magnetic field is virtually impossible. In that sense, use
of the superconductive coil 1 is very effective.

[0041](3) It is only necessary for the rotor 2 as the support object to
include the ferromagnetic body 2a made of steel or the like. It is also
advantageous in that no specific material is necessitated.

[0042](4) Use of the superconductive coil 1 allows to easily obtain
circular magnetic field distribution having extremely less distortion.
Accordingly, from such viewpoint, there is a large advantage over the
combination of a permanent magnet and superconductive bulk as in the
conventional constitution. Use of the circular superconductive coil 1
also provides such an advantage that no eddy current loss or hysterisis
loss may occur in principle, even if the rotor 2 having the ferromagnetic
body 2a is rotated while non-contact thrust force is maintained. That is,
as far as the rotation shaft 2b of the rotor 2 coincides with the coil
center axis 1a, there is no change in magnetic field in respective
portion of the ferromagnetic body 2a even if the rotor 2 is rotated.
Thus, rotational resistance due to magnetic factors never occurs.

Variation of First Embodiment

[0043]FIG. 2 is a schematic end view of the superconductivity utilizing
support mechanism in variation of the first embodiment.

[0044]As in the embodiment shown in FIG. 1, the superconductive coil 1 is
arranged to enclose the portion where the diameter of the rotor 2 is the
largest, that is, the outer periphery of the disk-shaped ferromagnetic
body 2a. However, in the case of large machinery, the constitution shown
in FIG. 2 is also effective.

[0045]The superconductivity utilizing support mechanism shown in FIG. 2 is
provided with a superconductive coil 21, a rotor 22 including a
ferromagnetic body 22a made of steel or the like, a cryogenic container
23 that accommodates the superconductive coil 21, a control type magnetic
bearing 25, and a casing 27 that accommodates the superconductive coil
21, the rotor 22, the cryogenic container 23, and the control type
magnetic bearing 25.

[0046]The rotor 22 in the present variation is a flywheel. A rotation
shaft 22b is provided to penetrate the center of the rotor 22. The
ferromagnetic body 22a is attached to the rotation shaft 22b in a fashion
concentric to the rotor 22. In comparison between the outer diameter of
the ferromagnetic body 22a and the outer diameter of the rotor 22, the
outer diameter of the rotor 22 is substantially larger than the outer
diameter of the ferromagnetic body 22a. That is, the purpose of this
constitution is to rotate the large-sized rotor 22. However, the rotor 22
is supported in a thrust direction by the ferromagnetic body 22a.
Accordingly, the regular annular superconductive coil 21 is arranged to
enclose the ferromagnetic body 22a. Particularly, an annular member 26
having a substantially U-shaped cross section is fixed to the inner
peripheral surface of the casing 27. The cryogenic container 23 is
retained by the annular member 26. The superconductive coil 21 is
disposed within the cryogenic container 23.

[0047]The ferromagnetic body 22a has a substantially columnar shape, but
with flange portions 221a formed at its upper and lower ends. Thus, the
ferromagnetic body 22a has a vertically symmetric shape. The flange
portions 221a are formed at such positions as to be able to face convex
portions 26a formed on upper and lower portions of the aforementioned
annular member 26 having a substantially U-shaped cross section. The
annular member 26 includes a ferromagnetic body and has a vertically
symmetric shape. The convex portions 26a function as a magnetic path of a
magnetic force generated by the superconductive coil 21 disposed within
the cryogenic container 23 retained by the annular member 26.
Accordingly, if the flange portions 221a of the ferromagnetic body 22a
are in positions to face the convex portions 26a of the annular member
26, the center plane S1 of the superconductive coil 21 and the center
plane S2 of the ferromagnetic body 22a coincide with each other. Axial
magnetic attraction does not work. However, if the center plane S1 of the
superconductive coil 21 and the center plane S2 of the ferromagnetic body
22a are separated, axial magnetic attraction works.

[0048]In the superconductivity utilizing support mechanism having the
above constitution, the same effects can be obtained as those in the
superconductivity utilizing support mechanism shown in FIG. 1. The
constitution is effective in floating and supporting the rotor 22 which
is the large-sized flywheel as noted above. That is, for example, if the
rotor 22 has to include a ferromagnetic body and the superconductive coil
21 has to be arranged to enclose the outer periphery of the rotor 22, the
size of the superconductive coil 21 also has to be large. However, there
may be cases in which such large sized superconductive coil 21 is not
necessary upon exertion of magnetic attraction for supporting the rotor
22. Accordingly, to cope with such cases, the ferromagnetic body 22a
having a smaller outer diameter than the rotor 22 may be separately
prepared. Then, bearing force in a thrust direction may be obtained by
magnetic attraction between the ferromagnetic body 22a and the
superconductive coil 21, as noted above. In this manner, the
superconductive coil 21 is inhibited from becoming unnecessarily large.

Second Embodiment

[0049]FIG. 3(a) is a schematic perspective view of a superconductivity
utilizing support mechanism according to a second embodiment. FIG. 3(b)
is an end view taken from a section A-A of FIG. 3(a).

[0050]In the aforementioned first embodiment, particular examples of the
present invention have been described which is implemented as a support
mechanism of a rotor. In the second embodiment, a particular example will
be described in which the present invention is implemented as a support
mechanism of a movable body.

[0051]As shown in FIG. 3, the superconductivity utilizing support
mechanism is provided with a movable body 33 including a superconductive
coil 31, and a track 32 including a ferromagnetic body 32a. FIG. 3 only
shows the superconductive coil 31 section. However, the movable body 33
is also provided with not shown components, in addition to the
superconductive coil 31. Since it is sufficient to show the
superconductive coil 31 section for explanation on a support mechanism
section, FIG. 3 does not show all of the movable body 33. The track 32 is
composed from two ferromagnetic bodies 32a in the form of rectangular
plates which are so arranged in parallel that planes of the ferromagnetic
bodies 32a are faced to each other. The ferromagnetic bodies 32a in this
case may be made of steel which thus constitute two steel rails.

[0052]The movable body 33 is guided along a plane (guide plane) S12 which
includes a center axis (coil center axis) 31a of the superconductive coil
31 and an axis 33a in a direction of travel of the movable body 33. The
movable body 33 is also constituted to slide in a direction of the coil
center axis 31a. Detail is not shown as to the constitution of being
guided along the guide plane S12 and slid in a direction of the coil
center axis 31a. However, the schematic constitution is shown below. That
is, the movable body 33 has a guide wheel at its lower end, for example.
A rotation direction of the guide wheel is directed only to a direction
of travel of the movable body 33. Originally, there is no vertical
restraint force in such guide wheel. Therefore, if the guide wheel is
rotated and is on the move toward the direction of travel, the movable
body 33 can relatively easily slide in a vertical direction. Thereby, the
movable body 33 is guided along the guide face S12, and is able to slide
in a direction of the coil center axis 31a.

[0053]The superconductive coil 31 is constituted like a race track, and
disposed between the two ferromagnetic bodies 32a (steel rails) in the
form of rectangular plates of the track 32. Particularly, the
superconductive coil 31 is disposed within a not shown cryogenic
container, and the superconductive coil 31 is placed between the
ferromagnetic bodies 32a. More specifically, the superconductive coil 31
of the movable body 33 is arranged in such a predetermined range that
magnetic attraction may become stronger as a center plane (ferromagnetic
body center plane) S13 of the ferromagnetic bodies 32a and a center plane
(coil center plane) S11 of the superconductive coil 31 are separated away
in a direction of the coil center axis 31a. Thereby, the movable body 33
is supported in a direction of the coil center axis 31a. As in the case
of the aforementioned first embodiment, the coil center plane S31 does
not necessarily coincide with a geometric center of the superconductive
coil 31 in general. However, in the present embodiment, the geometric
center and the coil center plane S11 coincide with each other since the
superconductive coil 31 is symmetrically formed. Also, the coil center
axis 31a extends in a direction of a normal line of the coil center plane
S11. In the ferromagnetic bodies 32a of the present embodiment, two
members having an identical shape are symmetrically disposed. Thus, as
shown in FIG. 3(b), a geometric center plane of the two ferromagnetic
bodies 32a in the form of rectangular plates is referred as the
ferromagnetic body center plane S13.

[0054]Here, the meaning of "the superconductive coil 31 of the movable
body 33 is arranged in such a predetermined range that magnetic
attraction may become stronger as the ferromagnetic body center plane S13
and the coil center plane S11 are separated away in a direction of the
coil center axis 31a" is the same as in the case of the aforementioned
first embodiment. That is, as shown in FIG. 3(b), if the ferromagnetic
body center plane S13 does not coincide with the coil center plane S11,
magnetic attraction is generated which pulls back the ferromagnetic
bodies 32a toward such a direction that the ferromagnetic, body center
plane S13 and the coil center plane S11 may coincide with each other.
However, it can be said that "magnetic attraction becomes stronger as the
ferromagnetic body center plane S13 and the coil center plane S11 are
separated away in a direction of the coil center axis 31a (that is, as
the ferromagnetic body center plane S13 is drawing away from the coil
center plane S11 in a direction of the coil center axis 31a)" if a
distance between the ferromagnetic body center plane S13 and the coil
center plane S11 is in a predetermined range. However, outside the
predetermined range, "magnetic attraction becomes weaker as the
ferromagnetic body center plane S13 is drawing away from the coil center
plane S11 in a direction of the coil center axis 31a". Accordingly, in
the present embodiment, the superconductive coil 31 of the movable body
33 is arranged within such a predetermined range that "magnetic
attraction may become stronger as the ferromagnetic body center plane S13
and the coil center plane S11 are separated away in a direction of the
coil center axis 31a" as in the former description.

[0055]Such arrangement offers an essentially stable and strong bearing
force in floating and supporting the movable body 33 in a direction of
the coil center axis 31a.

[0056]Also, such arrangement provides the same advantages as below as in
the case of the aforementioned first embodiment.

[0057](1) In the case of the conventional constitution, it is difficult to
raise precision of the shape, etc. of both the permanent magnet and the
superconducting bulk. There is a problem in stable support. In contrast,
the superconductivity utilizing support mechanism according to the
present embodiment utilizes the superconductive coil 31. In the case of
the superconductive coil 31, it is easy to raise precision in shape. It
is advantageous in stable float and support.

[0058](2) In the case of the support mechanism utilizing superconductive
bulk, there is limitation in manageable weight. Such support mechanism is
not realistic for use with a large-sized support object. On the other
hand, the present embodiment utilizes the superconductive coil 31. In the
case of the superconductive coil 31, it is comparatively easy to generate
a strong magnetic field. It is also comparatively easy to obtain the
large-sized the superconductive coil 31. Accordingly, it is easy to
relatively increase manageable weight. As such, without use of the
superconductive coil 31, the coil capable of generating a necessary
magnetic field may become very large when weight of a support object is
increased, or, depending on the weight of the support object, generation
of a necessary magnetic field is virtually impossible. In that sense, use
of the superconductive coil 31 is very effective.

[0059]As noted above, the present embodiment is suitable for such cases
that a support object is large-sized and heavy weighted. Thus, it is very
advantageous if the movable body 33 is assumed as a linear motor vehicle,
for example.

[0060](3) Also, it is only necessary for the track 32 to include the
ferromagnetic bodies 32a made of steel or the like. It is also
advantageous in that no specific material is necessitated.

Third Embodiment

[0061]FIG. 4(a) is a schematic end view of a permanent magnet utilizing
support mechanism according to a third embodiment.

[0062]As shown in FIG. 4(a), the permanent magnet utilizing support
mechanism is provided with a ring permanent magnet 51, steel rings 56 as
"ferromagnetic body rings" provided above and below the permanent magnet
51, a rotor 52 including an attracted steel 52a as a "ferromagnetic
body", a mechanical bearing 55, and a casing 57 that accommodates the
permanent magnet 51, the steel rings 56, the rotor 52, and the mechanical
bearing 55. The steel rings 56 and the attracted steel 52a may be formed
as ferromagnetic bodies made of other than steel.

[0063]The rotor 52 is a columnar flywheel. A rotation shaft 52b is
provided to penetrate the center of the rotor 52. The mechanical bearing
55 that utilizes a bearing supports the rotation shaft 52b both at an
upper end and a lower end of the rotation shaft 52b. Thereby, the rotor
52 is rotatably supported on the coil center axis 1a.

[0064]Not the mechanical control bearing 55 as such but a control type
magnetic bearing 65 utilizing an electromagnet or the like may be also
adopted as shown in FIG. 4(b). Use of the control type magnetic bearing
65 utilizing an electromagnet or the like can also provide non-contact
support for the rotation shaft 52b of the rotor 52. Also, even an air
bearing can achieve a non-contact bearing.

[0065]The attracted steel 52a is attached to the rotation shaft 52b in a
fashion concentric to the rotor 52. In comparison between the outer
diameter of the attracted steel 52a and the outer diameter of the rotor
52, the outer diameter of the rotor 52 is substantially larger than the
outer diameter of the attracted steel 52a. The attracted steel 52a has a
substantially ring shape. However, flange portions protruding toward a
radial direction is formed at axially upper and lower ends of the
attracted steel 52a. The attracted steel 52a are formed into a vertically
symmetric shape (if the axial direction is assumed as a vertical
direction).

[0066]The ring permanent magnet 51 is formed into a regular annular shape
and axially magnetized. The steel rings 56 having a smaller inner
diameter than the ring permanent magnet 51 are fixed to the axially upper
and lower ends of the ring permanent magnet 51 in a concentric fashion.
Thereby, as is also clear from FIG. 4(a), if the ring permanent magnet 51
and the steel ring 56 are assumed as a unit, there exist flange portions
(steel rings 56 in fact) protruding toward a radial direction at axially
upper and lower ends of the unit. The unit is also formed into a
vertically symmetric shape (if the axial direction is assumed as a
vertical direction).

[0067]The steel rings 56 corresponding to flange portions protruding
radially inward if the permanent magnet 51 and the steel rings 56 are
assumed as a unit and the flange portions protruding radially outward of
the aforementioned attracted steel 52a are disposed in positions to face
each other.

[0068]The steel rings 56 function as a magnetic path of magnetic force
generated by the permanent magnet 51. The steel rings 56 are arranged to
face the flange portions of the attracted steel 52a. Thus, when the steel
rings 56 and the flange portions of the attracted steel 52a are in
positions to face each other, the center plane of the ring permanent
magnet 51 and the center plane of the attracted steel 52a coincide with
each other. In this case, axial magnetic attraction does not work.
However, when the steel rings 56 and the flange portions of the attracted
steel 52a are relatively shifted from the facing position in the axial
direction, the center plane of the ring permanent magnet 51 and the
center plane of the attracted steel 52a are separated. In this case,
axial magnetic attraction works.

[0069]The attracted steel 52a of the present embodiment is formed into a
vertically symmetric substantially ring shape (if the axial direction is
assumed as a vertical direction). Thus, the geometric center plane of the
attracted steel 52a corresponds to a "center plane of the ferromagnetic
body" in claims. Also, if the permanent magnet 51 and the steel ring 56
are assumed as a unit, the unit is also formed into a vertically
symmetric shape (if the axial direction is assumed as a vertical
direction). Thus, the geometric center plane of the permanent magnet 51
corresponds to a "center plane of the permanent magnet ring" in claims.

[0070]Such constitution allows to obtain essentially stable bearing force
when the rotor 52 is floated and supported in a direction of the center
axis 52b. In the third embodiment, the permanent magnet 51, and not the
superconductive coil 1, 21, 31 as in the first and the second
embodiments, is utilized. Thus, it is possible to obtain bearing force in
a thrust direction by means of an inexpensive and extremely easy
constitution.

[0071]Use of the superconductive coil 1, 21, 31 as in the first and the
second embodiments is suitable for supporting a relatively heavy support
object. However, use of the permanent magnet 51 as in the third
embodiment is very effective if applied to a relatively light support
object.

[0072]The mechanical bearing 55 in FIG. 4(a) and the control type magnetic
bearing 65 in FIG. 4(b) are proposed as a radial bearing. Adoption of the
mechanical bearing 55 as in FIG. 4(a) simplifies the constitution of a
support mechanism. On the other hand, adoption of the control type
magnetic bearing 65 as in FIG. 4(b) can achieve a completely non-contact
support mechanism with little damage as a flywheel.

[0073][Others]

[0074]The embodiments of the present invention are described in the above.
However, the present invention can take various modes.

[0075]For instance, the present invention can be implemented as a support
mechanism of a propulsion shaft of a large-sized ship, as an example of
application of the superconductivity utilizing support mechanism of the
present invention. The propulsion shaft of a large-sized ship transmits
rotational power. At the same time, large thrust force is applied to the
propulsion shaft by screw rotation. Thus, if such large thrust force can
be supported in a non-contact manner by utilizing the constitution as in
the first embodiment, excellent equipment would be provided without care
for wear.

[0076]In the third embodiment, a particular example is described in which
the present invention is implemented as a support mechanism of a rotor.
However, in the case of such support mechanism utilizing a permanent
magnet as well, the present invention can be applied in the same manner
to a support object, aside from a rotor, which is necessary to be axially
supported in a non-contact manner.